A pointer for function

Hello, I am having problem with this code (CPP), i can`t understand why i cannot refer a pointer function. Anyone can help me and can say me the correct way?

//// Here is FunctionPointer.h

#ifndef FUNCTIONPOINTER_H
#define FUNCTIONPOINTER_H

class FunctionPointer
{
public:
    int sum(int,int);
    int product(int,int);
    int (*pointer)(int,int); // this pointer will be refer sum or product.
    FunctionPointer();
};

#endif // FUNCTIONPOINTER_H

/// - Here is the functionpointer.cpp

#include "functionpointer.h"
#include <iostream>
using namespace std;
FunctionPointer::FunctionPointer()
{

}

int FunctionPointer::product(int a,int b){
   return (a*b);
}
int FunctionPointer::sum(int a,int b){
    return (a+b);
}

int main(){
    FunctionPointer f;
    f.pointer = f.product;
    cout << f.pointer(2,3) << endl;
    return 0;
}

///
error (Gnu C++): argument of type `int(FunctionPointer::)(int,int)` does not match `int(*)(int,int);

Thanks.

Duthomhas (13206)

You are trying to create a function pointer to a member function.
Read here for more on making pointers to member functions:
http://www.newty.de/fpt/

Hope this helps.

m4ster r0shi (2201)

Turn this -> int (*pointer)(int,int); into this -> int (FunctionPointer::*pointer)(int,int);

Also, turn this -> f.pointer = f.product; into this -> f.pointer = &FunctionPointer::product;

Finally, turn this -> f.pointer(2,3) into this -> (f.*(f.pointer))(2,3)

That should do it ;)

Last edited on

ArchV (4)

Thanks guys this was very useful

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A pointer for function